Population genomics of mycobacterium ieprae reveals a new genotype in Madagascar and the Comoros

Human settlement of Madagascar traces back to the beginning of the first millennium with the arrival of Austronesians from Southeast Asia, followed by migrations from Africa and the Middle East. Remains of these different cultural, genetic, and linguistic legacies are still present in Madagascar and other islands of the Indian Ocean. The close relationship between human migration and the introduction and spread of infectious diseases, a well-documented phenomenon, is particularly evident for the causative agent of leprosy, Mycobacterium leprae. In this study, we used whole-genome sequencing (WGS) and molecular dating to characterize the genetic background and retrace the origin of the M. leprae strains circulating in Madagascar (n = 30) and the Comoros (n = 3), two islands where leprosy is still considered a public health problem and monitored as part of a drug resistance surveillance program. Most M. leprae strains (97%) from Madagascar and Comoros belonged to a new genotype as part of branch 1, closely related to single nucleotide polymorphism (SNP) type 1D, named 1D-Malagasy. Other strains belonged to the genotype 1A (3%). We sequenced 39 strains from nine other countries, which, together with previously published genomes, amounted to 242 genomes that were used for molecular dating. Specific SNP markers for the new 1D-Malagasy genotype were used to screen samples from 11 countries and revealed this genotype to be restricted to Madagascar, with the sole exception being a strain from Malawi. The overall analysis thus ruled out a possible introduction of leprosy by the Austronesian settlers and suggests a later origin from East Africa, the Middle East, or South Asia.Immunogenetics and cellular immunology of bacterial infectious disease

Chromoblastomycosis and sporotrichosis, two endemic but neglected fungal infections in Madagascar

International audienceChromoblastomycosis and sporotrichosis are endemic fungal infections of tropical and subtropical regions, including Madagascar. The causal fungi develop in the soil or on plants and infect humans through wounds, either directly (wounding by the plant, through thorns, for example), or through the contact of an existing wound with contaminated soil. For this reason, the lesions predominantly occur on the limbs, and these fungi principally infect people working outside with bare hands and/or feet. The subcutaneous lesions of chromoblastomycosis are initially nodular, subsequently becoming warty, tumoral, cauliflower-like and pruriginous, which promotes dissemination. The chronic nature of the infection and its progression over long periods lead to highly disabling lesions in essentially rural and agricultural populations. The lesions of sporotrichosis are also nodular, but more ulcerous, and they form an extended chain following the route of the lymph vessels. Pus, squamous or skin biopsy specimens are used for the mycological examination of these mycoses. Treatment depends on the severity and form of the lesions and is based on antifungal drugs sometimes combined with physical methods. There has been no study of these infections for more than two decades in Madagascar, despite the large numbers of cases seen by doctors in all parts of the island. The nature, diversity and distribution of the plants responsible for contamination have not been described in Madagascar. In this review, we described these two endemic mycoses in terms of their epidemiological, mycological, clinical and therapeutic characteristics, focusing particularly on Madagascar, which is one of the leading foci of these two infections worldwide

Population Genomics of Mycobacterium leprae Reveals a New Genotype in Madagascar and the Comoros

Human settlement of Madagascar traces back to the beginning of the first millennium with the arrival of Austronesians from Southeast Asia, followed by migrations from Africa and the Middle East. Remains of these different cultural, genetic, and linguistic legacies are still present in Madagascar and other islands of the Indian Ocean. The close relationship between human migration and the introduction and spread of infectious diseases, a well-documented phenomenon, is particularly evident for the causative agent of leprosy, Mycobacterium leprae. In this study, we used whole-genome sequencing (WGS) and molecular dating to characterize the genetic background and retrace the origin of the M. leprae strains circulating in Madagascar (n = 30) and the Comoros (n = 3), two islands where leprosy is still considered a public health problem and monitored as part of a drug resistance surveillance program. Most M. leprae strains (97%) from Madagascar and Comoros belonged to a new genotype as part of branch 1, closely related to single nucleotide polymorphism (SNP) type 1D, named 1D-Malagasy. Other strains belonged to the genotype 1A (3%). We sequenced 39 strains from nine other countries, which, together with previously published genomes, amounted to 242 genomes that were used for molecular dating. Specific SNP markers for the new 1D-Malagasy genotype were used to screen samples from 11 countries and revealed this genotype to be restricted to Madagascar, with the sole exception being a strain from Malawi. The overall analysis thus ruled out a possible introduction of leprosy by the Austronesian settlers and suggests a later origin from East Africa, the Middle East, or South Asia